I use to take my pup out 5 times a day, and he was already potty trained, I just had the time.

I took him out at 7, min for 45 mins max 2 hours, then again at 10:30 for a quick 15-20 min potty break/walk, again at 1:30 (on Wednesdays it was 12:30) for another 15-20 min break, 6:30 when I got home for an hour and a half, sometimes 3, and then out last outing at 11 pm. It's about the same as yours and it worked well for my little one.
He came potty trained so I don't know how long it took.